Door latch with pivoted-cam locking plate



July 5, 1966 c. STECKLE 3,259,413

DOOR LATCH WITH PIVOTED-CAM LOCKING PLATE Filed Jan. 22, 1964 0 O (Q) 9 a 3 I 6 I 9 l /3' l 7k 2 I 5 4 l2 l8 llVVE/VTOR CHARLES ST'ECKLE A homey United States Patent 3,259,413 DOOR LATCl-ll WITH PIgOTED-CAM LOCKING PL TE Charles Steckle, Allison Park, Pa., assignor to United States Steel Corporation, a corporation of Delaware Filed Jan. 22, 1964, Ser. No. 339,400 1 Claim. (Cl. 292-132) This invention relates especially to a device which provides for a remotely operated, positive acting apparatus for opening and closing bottom discharging cinder cleanout doors and the like, such as are found in soaking pits associated with slab mills in the steel industry. However, other applications will be apparent.

More particularly, it is an object of the invention to provide a self-locking latch for soaking pit clean-out doors which is relatively unaffected by heat distortion of pit bottoms, due to compactness and simplicity of parts, as compared to known existing cinder clean-out door latching devices, which latter distort and become inoperative, in which cases personnel are exposed to potential hazards of heat and hot cinders while work-ing under pits in returning doors and latching mechanism to operative condition.

The device of the invention is generally a self-latching mechanism for a vertically opening door, and is further characterized by having a pivoted-cam locking plate adapted to impart capability of remote operation. It is more fully described in conjunction with the accompanying drawing, in which:

FIGURE 1 is a view in elevation of a self-closing soaking pit clean-out door and related remotely operated latching mechanism, showing the door secured in closed position.

FIGURE 2 is identical with FIGURE 1, except that it depicts the latch in door-releasing position.

FIGURE 3 is also identical with FIGURE 1, with the exception that the solid lines thereof illustrate the position of the latching mechanism with the door open and the broken lines show the door during closing, just prior to tripping the latch.

Referring to the figures, with particular attention to FIGURE 1, wherein is shown a clean-out spout 1 having door 2 hingeably attached thereto by pivot 3. The door carries counterweight 4.

The door has lip 5 adapted to engage bearing surface 6 of the inwardly projecting portion of hook member 8, whereby the door is latched in closed position. The aforementioned projection is also partially defined by inwardly and upwardly sloping beveled edge 7.

In describing the latch assembly, inwardly and upwardly, as used above, and words of similar import, refer to space relationship relative to the door.

Hook member 8 is attached at its upper end by pivot 9 to supporting structure 10, which latter may be conveniently secured to clean-out spout 1 and adjacent structure. Hook member 3 is of such configuration and mass, and is pivoted sufficiently inboard of the vertical, so that it is urged toward the door by gravity.

Another principal component of the latch assembly is generally horizontal lock plate 11 of substantial mass which is pivotally attached 12 at its outer end to latch mechanism support-ing structure 10. At the near end of the lock plate there is a generally vertical cam slot which engages a follower 13 located near the far lower portion of hook member 8.

Lock plate '11 has attached thereto cable 14 passing over sheave 15 to afford means for lifting lock plate .11 by remote control. Other means (not shown) of lifting lock plate 11 are contemplated in certain instances, for example an extension shaft rigidly attached to the lock 3,259,413 Patented July 5, 1966 plate at 12 and having a right angle lever attached at its opposite end.

The essential details and design criteria for the cam slot which engages follower 13, may be readily understood from a consideration of the operation of the device.

With the door latched, as shown in FIGURE I, lock plate 11 falls by gravity so that follower v1.3 is at the apex of the'cam slot. This portion of the cam slot has a far edge 16 positioned to engage follower 13 to prevent outward movement of hook 8 and its consequent accidental dislodgment from door lip 5.

With particular reference to FIGURE 2, it may be noted that the cam slot [contour has a neutral section from its apex to point 17 which permits the lock plate 111 to be freely raised, without disturbing the position of book member 8, whereby substantial momentum may be imparted to the look plate. This sect-ion will generally permit free upward travel of the lock plate for a distance of several times the diameter of the cam follower.

Also, with particular reference to FIGURE 2 it will be apparent that upon further upward movement of lock plate 11, cam follower 13 engages the near surface of the cam slot at point 17, where the contour of the slot becomes generally downward and outward, to provide outward movement of hook member 8 by a generally wedging action. This out-ward contour continues to point 18, the position of which is determined by the generation of the necessary outward movement of hook member 8 to permit door lip 5 to clear bearing surface 6.

The aforementioned provision for free upward travel of lock plate 11, between the cam slot apex and point 17, is to permit imparting sufficient momentum to the lock plate to create the effect of a hammer blow at point 17, which greatly multiplies the opening force of the latch,

As is particularly evident from FIGURE 3, additional elevation of lock plate M, with the door swung open, permits cam follower .13 to pass through a passage in the cam slot from point 18 to stop 19, which the follower does due to the previously mentioned tendency of hook member 8 to swing inwardly, unless restrained.

Beveled edge 7 of book member 8 is adapted to wedge outwardly hook member 8 upon travel of the outer edge of lip 5 in contact with said edge, in self-latching operation. Stop 19 is located so as to retain hook member 8 in position so that edge 7 is in readiness to functionally engage door lip 5, upon closing of the door, as shown in FIGURE 3.

Edge 7 is so configured as to cause cam follower 13 to clear cam slot point 18, thus allowing lock plate 11 to fall until the cam slot apex is in contact with cam follower 13, while book 8 swings inwardly, upon lip 5 clearing edge 7, whereupon bearing surface 6 resumes its door support function.

While an operative example of this invention has been described with some particularity, it will be understood that modifications may be made therein, within the scope of the following claim.

I claim:

A self-locking latch for soaking pit clean-out door and the like, comprising:

(a) structure for the support of latch elements;

(b) a generally vertical hook member pivotally attached at its upper end to said structure, said member being at such configuration and mass, and said pivot being so located, that the hook member is urged toward said door by gravity;

(c) a projection on said hook member having an upper bearing surface adapted to support the lip of said door in closed position;

(d) a lower outwardly beveled portion of said projection adapted to engage the door during closing, said beveled portion, upon engagement with said door, being capable of imparting a pivotal retreating movement to said hook member upon striking same;

(e) a cam follower near the lower extremity of the hook member;

(f) a generally horizontal lock plate of substantial mass pivotally mounted at its outer end upon the latch support structure, said lock plate having a generally vertical cam slot at the near end of said lock plate, generally opposite, horizontally, with respect to said lock plate pivot, said cam slot engaging said cam follower;

(g) an upper section of said cam slot with apex adapted to retain said hook member in door-securing position, said upper section being of sufficient height to provide sufficient headroom to permit rapid upward acceleration of the lock plate whereby substantial momentum may be imparted thereto;

(h) beneath said upper cam slot section a cam slot section with near edge outwardly sloping sufiiciently to insure a combined hammer blow and wedging action to said hook, upon upward acceleration of said lock plate, adapted to free the hook from the door;

(1) at the lower terminus of said outward-1y sloping cam section an inwardly extending substantially horizontal slot adapted to prevent the further fall of said lock plate and to hold the hook member with its said lower beveled portion in door-striking position; and

(j) means for remotely raising said lock plate.

References Cited by the Examiner UNITED STATES PATENTS 499,529 6/1893 Dyer 2921 11 1,529,236 3/1925 Brady 292131 1,582,561 4/1926 Vandrey 292-235 2,547,319 4/1951 Harding 292131 20 IOSEPHD. SEERS, Primary Examiner.

J. R. MOSES, Assistant Examiner. 

